Method of treating petroleum distillates



Patented Mar. 9, 1937 UNITED STATES PATENT OFFICE Frank Gardner, Dallas,Tex.

No Drawing.

Application November 11, 1935,

Serial No. 49,287

4 Claims.

This invention relates to the treating of petroleum distillates and ithas particular reference to a method for treating gasolene and kerosenefor the removal of objectionable sulfur compounds 5 therefrom.

The principal object of the invention is to provide a method fortreatment of distillates whereby mercaptans are converted to disulfidesand whereby the sulfur content of the finished prod:

not is considerably less than when conventional methods are employed.

Another object of the invention is to provide a method for treatment ofdistillates whereby the conversion to disulfides may be effected atlittle cost and whereby the refined distillate from a given grade ofcrude oil will have a uniform quality.

With the foregoing objects as paramount, the invention has particularreference to the salient steps in the method which will become manifestas the description proceeds;

In the manufacture of gasolene and kerosene, the conventional method ofremoving hydrogen sulfide is by washing with water or a solution 5 ofsodium hydroxide, while mercaptans are changed to the less objectionabledisulfides by the use of sodium plumbite, known as doctor solution, andsulfur according to the following equations:

Let R represent a hydrocarbon group such as ethyl (Cal-I5).

NagPbog (Mercaptans) (Sodium plumbite) (RS)2Pb 2NaOH (Lead mercaptide)(Sodium hydroxide) (RShPb s 2RS PbS (Lead mercaptide) (Sulfur)(Disulfido) (Lead sulfide) It will be understood that, althoughtheoretically the latter reaction will go to completion as shown, inactual refinery practice an excess of sulfur is often used, eitherthrough inadvertence or in order to drive the reaction to completion. Anexcess of sulfur in the distillate is most undesirable due to theresultant corrosive action on the 45 metal of internal combustionengines.

The present invention relates. to a method of converting mercaptans todisulfides which does not require the addition of sulfur, therebyprecluding the possibility of an off corrosion prod 50 uct due to thiscause. The treating compounds by which this may be accomplished are thealkaline plumbates, either sodium or potassium metaplumbate (NazPbOa) orthe corresponding orthoplumbate, such as Na4PbO4.

The reactions with meta-plumbate may be represented:

2RSH NazPbOs (Mercaptans) (Sodium meta-plumbate) 2RS Na,Pb0, 11,0(Disulfides) (Sodium plumbite) (Water) The action of sodiumortho-plumbate and mercaptans may be represented:

2RSH Na Pbo (llfercaptans) (Sodium orthoumbate) ans Na Pbo 2NaOH(Disulfides) (Sodium plumbite) (Sodium hydroxide) The chief advantagesof the ortho-plumbate over the meta-plumbate are that the reaction timeis much less and that the ortho compound may be regeneratedelectrolytically at less expense due to the formation of less molecularoxygen. It will be understood that when orthoplumbate is used as theprincipal treating reagent, the solution will in general contain anappreciable percentage of the meta-plumbate as well.

Manifestly, the method described is capable of considerable modificationand such modification as may fall within the scope of the appendedclaims is considered within the spirit and intent of the invention.

What is claimed is:

1. A method for converting mercaptans to disulfides in petroleumdistillates without the addition of sulfur thereto, which comprisessubjecting said distillates to the action of an aqueous solution of analkali metal plumbate.

2. A method for removing mercaptans from petroleum distillates withoutthe addition of sulfur thereto, which comprises subjecting saiddistillates to the action of an aqueous solution of an alkali metalmeta-plumbate.

3. A method for treating petroleum distillates for the removal ofobjectionable sulfur compounds therefrom which comprises subjecting saiddistillates to the action of an aqueous solution of an alkali metalortho-plumbate without the addition of sulfur to said distillates.

4. A method for insuring against excessive corrosive properties inpetroleum distillates which, comprises subjecting said distillates tothe action of an aqueous solution of sodium plumbate without theaddition of sulfur to said distillates.

FRANK GARDNER.

